Internet protocol (IP) backbone networks consist of sets of nodes which are connected by high-speed links. These nodes route traffic through the network and also connect the customer premise to the IP network. The cost of access from the customer premise to the node is significant portion of the service cost. This cost is a function of the distance between the customer premise and the node. Ideally, each customer premise is connected to the node nearest to his location, termed “the planned node.” Therefore, nodes are typically geographically distributed so that the aggregate access cost from all the customer premises is minimized.
Customers access the network via various different mechanisms, such as private lines, asynchronous transfer modes (ATMs), frame relay service (FRS), gigabit and fast Ethernet, etc. The requested access speeds vary widely within each access mechanism.
To accommodate various access mechanisms and speeds, each node consists of a number of access routers with various types of ports connected to one or two backbone routers, which links the node to backbone routers of other nodes. Each type of port can only be used for the specific access mechanism and speed for which it is designed.
To efficiently operate the network, the quantity of each port type at each node should match customer demand. The determination of the demand is tedious because it must be forecast for each port type independently by a time series forecast. If the demand for a particular port type turns out to be higher than the forecasted value, the demand cannot be accommodated by another port type, even if the node has plenty of excess capacity in other types of ports.
It is difficult to precisely forecast the number of ports of each type at each node. Therefore, provisioning processes usually have mechanisms to deal with the forecast errors. If the planned node does not have capacity, the customer premise is connected to the next nearest node that has the desired port, “the alternate node.” Such a connection is termed “a mis-homed connection.” If and when the planned node has available capacity, the connection between the alternate node and the customer premise is terminated, and the customer premise is connected to the planned node. Connection to the planned node is termed “re-homing.”
However, the mechanism of current provisioning processes has several disadvantages. For example, re-homing is very expensive. Re-homing involves building a circuit from the customer premise to the planned node, going through the test and turn up process, and disconnecting the connection between the customer premise and the alternate node. Typically, a dedicated team needs to focus on finding mis-homed connections, and re-homing customer premises to their planned nodes. Also, mis-homed connections are costly since a customer only pays for the access circuit from his premise to the nearest node. Thus, a company needs to absorb the cost of providing access to a sub-optimal node, i.e. an alternate node.
Another disadvantage of current provisioning processes is that they are prone to cascading effects. That is, when a node gets more customer requests than it can accommodate, the excess demand spills over to a neighboring node. Unless that neighboring node has opposite forecast error, i.e. greater capacity than the demand, a capacity shortage is created at such node, and the excess demand spills over to still other nodes.
A further disadvantage of current provisioning processes is that it increases the exception routes, thereby making the network inefficient. All customers connecting to one router get the address space for their network from the same IP address block. In this way, a router can advertise just one block for all the customer networks. However, in a re-home scenario, a customer connection moves from one node to another but the customer IP address block remains the same. In this scenario, the provisioning system has a choice. It can assign addresses either from the router by which the circuit is getting connected, or from the destination router after the re-home. In either case, exception routes need to be advertised when customer network is connected to the router with different IP address block. Such advertising requires valuable resources.
Accordingly, there remains a need for a method of efficiently utilizing ports capacities in an IP network.